1. Technical Field
The present invention relates to a microencapsulated particulate metal material for use in, for example, ink-jet metal wiring, and electronic equipment produced with the metal wiring, a method for producing the same, and an aqueous dispersion and an ink jet ink using the same.
2. Related Art
Metal particles such as metal nanoparticles and fine metal particles have been used, for example, for electrooptical apparatuses, conductive film wiring (metal wiring) of electronic equipment and coatings for films for use in display devices such as CRTs and liquid crystal displays.
For example, WO2002/013999 discloses a colloidal metal solution having a pH in the range of 8 to 14 and containing a low molecular weight sulfur compound present as a protective colloid on the surfaces of colloidal metal particles for the purpose of providing a colloidal metal solution of high concentration that has excellent dispersion stability with a small amount of a protective colloid in an industrially and economically advantageous manner, without an operation such as centrifugation.
Since metal particles such as these colloidal metal particles have high surface activity due to the quantum size effect, they fuse at low temperatures and tend to aggregate. For this reason, metal particles are generally stabilized for use by being coated with a dispersant on their surfaces. However, when metal particles are coated with a low molecular weight compound such as thiol, the ion tends to be eluted into the solvent, so that there is a fear that this ion may cause aggregation of the metal particles.
Further, semiconductors and other circuit elements are produced by forming circuit patterns, wiring patterns and other functional film patterns on silicon, glass, PET (polyethylene terephthalate) and other substrates. The pattern formation using ink jet technology is being used, since it enables formation of particularly minute film patterns and functional film patterns with a simplified process. When known metal particles are used for a metal particle ink for ink jet, the above-described problem may also arise and aggregation of the metal particles may reduce the adhesion of the particles to the substrate surface.